2004 250 efi - low compression on #6

[Horsquatch]

Understood, I’m going to put it back together with the new seals and recheck the compression. Any tips on re installing the head cover? Surface preparation and/or additional lubrication?

[Horsquatch]

Also are there any additives I should consider running through the system to help extend the life a bit?

[JOE54]

head bolts are one use only , replacement recommended

[Horsquatch]

Thanks Joe. Is there a Mercury part number for the head bolts, and Do you know the torque specs for them?

[XXXLTRP]

Thanks Joe. Is there a Mercury part number for the head bolts, and Do you know the torque specs for them?

It would be worth your effort/ time/ investment to buy the service book for your SN# from Don. I've been this deep and deeper into mine as well and the book answers all these questions. The head bolts are torque to yield/ "TTY" which means they have a torque value in inch or foot lbs plus an additional, 90 ,180 degree turn or some other specific specification degree turn as well as a sequence. EDIT - The book would have those details. I consider it an easy job with the right detailed specifications.

[Horsquatch]

Thanks TRP! I have the manual and I will definitely dig into it

[JOE54]

8m0045380 x 40 brace your self $$$$

[bass.man65]

Understood, I’m going to put it back together with the new seals and recheck the compression. Any tips on re installing the head cover? Surface preparation and/or additional lubrication?

If you put it back together like it is you didn't accomplish anything. I would pull that piston hone that cylinder and put new set of rings on it then put back together.